Such a fiber bundle is used, for example, in a device for scanning a document. The document is introduced under the first end face of the fiber bundle and an image of the part of the document lying under this end face is transmitted via the fiber bundle to a detection system arranged at the second end face. Due to a linear first end face of the fiber bundle this end is optimized for scanning the document over its full width, while the shape of the second end face is optimized for the detection system due to the different arrangement of the fibers. As a result a detection system, which is inexpensive because it is mass-produced, can be used, such as a CCD sensor element for a video camera. A device for scanning documents in which such a fiber bundle is present is described for example in U.S. Pat. No. 4,570,063.
The fibers used may be so-called "step-index" or "graded-index" fibers and may be manufactured from any suitable material, for example, glass, quartz or a synthetic material such as polymethyl methacrylate.
A method as described in the opening paragraph is known from "Patent Abstracts of Japan", Vol. 7, no. 249 (p. 234) [1394], Kokai no. JP-A 58-132705 in which an optical fiber is wound on a drum, while the adjacent turns are connected to each other by means of an adhesive and subsequently cut loose from the drum so that a sheet composed of optical fibers is produced. Subsequently one end of each fiber is loosened from the sheet and placed in an opening of a rectangular grid, while the fibers are again fixed with respect to each other by means of an adhesive and the rectangular end face thus formed is flattened and polished.
This known method is cumbersome and therefore expensive. After the sheet formed from optical fibers has been detached from the drum, each fiber must be separately introduced into the grid. Since such a fiber bundle has a very large number of fibers, this operation is time-consuming, the standard number for, for example a facsimile apparatus (group 3 in accordance with the CCITT standards i.e. the standards of the Comite Consultative Internationale de Telegraphic et Telephonie) is 1728. Moreover, this process is not continuous. After the fiber has been wound on the drum, the drum must be stopped to remove the manufactured sheet. Furthermore, each fiber in the fiber bundle is cut off twice, namely after the fiber has been wound on the drum and subsequently after the fibers have been placed in the grid. The fibers in the sheet formed have equal lengths while the fibers in a fiber bundle formed in this way have unequal lengths. This may cause problems when providing the fibers in the bundle without any tension and, in view of the large number of fibers, results in a quite considerable loss of material.